The present invention relates generally to a billboard and, more particularly, to a billboard which will spread a predetermined audio message to a person upon detecting the approach of the person and which has a minimized size so that it occupies only a small space in use.
Typically, a billboard is used as an advertising medium to introduce and promote goods for sale in a shop, store, drugstore, department store, and so on. At present, a billboard usually includes a piece of paper bearing a two-dimensional picture or drawing and attached to a backboard hung on a wall. The picture or drawing shows the outer appearance of the goods to be promoted. To achieve a higher advertisement effect, cubic models for the goods to be promoted have been used. However, these known billboards occupy more space and are costly and inconvenient to be replaced with new ones. The promotion effect achieved by these known billboards is constrained. There is a necessity for a billboard which is more attractive and allows the easy change of advertising pictures.